Caulking for Under a Toilet

Advantages

• Calking around the base of the toilet prevents unwanted water -- such as from an overflowing toilet -- from seeping beneath the toilet. If water gets under the toilet, it will become trapped and you will be unable to effectively clean it up. The water will eventually cause an unpleasant odor and may grow mold. Caulking also helps anchor the toilet to the floor by adhering it to the floor's surface.

Disadvantages

• Applying caulk all the way around the toilet will seal the area, which can make detecting a leaking toilet difficult or impossible until severe damage occurs. The water from the leak will work its way through the flooring beneath the toilet and cause wood damage or rot. A leak that occurs beneath the floor at the toilet's flange will never try to seep out from beneath the toilet, so the caulking will not mask such a leak.

Application

• When applying the caulk around the toilet, you should consider leaving a 1-inch gap open in the back of the toilet. The un-caulked gap will allow the water from any leak to run out from beneath the toilet. Before applying the caulk, you should make sure that the toilet is firmly affixed to the floor so there is no movement. You should choose a mildew-resistant silicone or latex caulk.

Flooring Types

• You should always use caulk around the base of a toilet that is affixed to a concrete floor. Concrete flooring is notoriously unlevel and the toilet will rarely sit flush on the concrete. Applying the caulk helps to fill in the gaps and make a cosmetically pleasing appearance. Avoid using caulk around a toilet that sits on wood flooring because the planks often buckle or move, which will make the caulking look unsightly. Wood flooring will also suffer more extensive damage from a leak than other flooring types, so detecting the leak immediately will give you time to fix it before damage occurs.